Tumor vaccine is a promising immunotherapy for solid tumors. Therapeutic tumor vaccines aim at inducing tumor regression, establishing durable antitumor memory, and avoiding non-specific or adverse reactions. However, tumor-induced immune suppression and immune resistance pose challenges to achieving this goal. In this article, we review multiple challenges currently faced in the development of therapeutic tumor vaccines, with a particular focus on anonymous antigen vaccines in situ as a new direction. We summarize the research progress in this area, aiming to provide a reference for future studies on tumor vaccines.